1. Field of the Invention
The present invention relates to a novel process for producing 3-cyanomethyl cyclopentanone derivatives which are useful precursors of fragrant components such as methyl jasmonoate, methyl dihydrojasmonate, etc.
2. Description of the Prior Art
The 3-cyanomethyl cyclopentanone derivatives having the formula ##STR1## wherein R.sup.1 represents hydrogen atom or an alkyl group, an alkenyl group or an alkynyl group and R.sup.2 represents hydrogen atom, an alkoxycarbonyl group or an acyl group are useful as the precursor of jasmonoides which mean the fragrant components in jasmine and analogous thereof, such as methyl jasmonoate, methyl dihydrojasmonate, etc. which impart the characteristic fragrances of jasmine [E. H. Polak, Cosmetics and Perfumery, 88, 46 (1973)]. These compounds have also been considered to be important as fragrant reinforcing substances.
Various processes for producing jasmonoids have been reported. [T. L. Ho. Syn. Commun., 4, 265 (1974)], for example, the synthesis of methyl jasmonoate from cyclopentanonenamine derivatives [E. Demole, et al., Helv. Chem. Acta, 45, 692 (1962)]; the process for reacting a neucleophilic reagent with a cyclopentanone derivative [G Buchi, et al., J. Org. Chem 36, 2021 (1971); A I Meyers, et al., J Org. Chem. 38, 175 (1973); A. E. Greene, et al., Tetrahedron Lett., 4867 (1976)], the synthesis from indanone derivatives [S. Torii et al., J. Org. Chem. 40, 462 (1975)], the process for using an intermediate obtained by an electrolysis of a norbornane derivative [S. Torii et al., J Org Chem. 40, 2221 (1975)].
These processes respectively have disadvantages that the starting materials are not easily obtained, the selectivity of the reaction is low in some cases, the reaction steps are lengthy, the expensive reagent is needed in some cases, the operation in the reaction is not easy, etc.
The inventors have studied the process for producing jasmonoids in industrial operation and have found the process for easily producing the 3-cyanomethyl cyclopentanone derivative having the formula (VI) which is useful as the precursor of the jasmonoids.